Ignitor



y 24, 1951 F. s. MILLER ET AL 2,561,670

IGNITOR Filed July 30, 1945 IN V EN TOR. 32' COLMA/V Z OLA FRED 5.MILLER BY CMQY February 8, l9 .14,"now abandoned.

and reliable ignition device for 'a 'rocket motor.

charge of fuel within the chamber, and --an--exhaust nozzle throughwhich the gases "resulting cartridge enclosing them of aninflammableIna--4 .a-suitable igniting charge which may ior-eexamplePatented July 24, 1951 s 1 tries IIGNITQR' I Fre'dSS. -Millcr,-Pasadena, Galif.,-'-,a1id-ColmanlZola.,

'Silver Spring, IMd assignorsi-to AerojetLEn- -gineeringicornoration,Azusa, ;.Galif;,-a2a -.cor oration ofiDelaware ,Applicationflulyfifl,1945;Serial him-6071688 :3 Claims. (Gl.310.2-";86:5)-

"This invention relates to rocket motors and more particularly-to meansforigniting the-propellant in the combustion chamber-of the motor. Theinvention 'is a continuation-in-part -of our co-pendingapplicatiom-Serial No.'-521-,'55'0,-filed *5 cap there is attacheda:suitable.exhaustznozzle "contain asphalt with potassium :perchloratemixed in it "as an .iOXidiZGI'. :In accordance with "good p'ractice, thei surface 4 f the propellant -is-made 'flat as shown. .Atthe: outerendiofr the 5 which is preferably of the De Lavalitypehaving -a venturishaped opening through .which gases irom the combustion of thepropellant-in V the chamber pass at high velocity.

The principal object is to provide an 'eifective Jet propelled devicessuch *as rocket motors ordinarily comprise a combustion "chamber, a

' -'the=-cap?to ignite the propellant charge; and. the

" ignitor shown is constructed according "to our invention. 'Tofit theignitorto the capthere is "provi'ded-asuitableboss"! which maybe securedto the "cap by welding 8 as shown and provided with a set of internalthreads to receive a plug member "9 of the ignitor. -'There is centrallyAccording to our invention wa -provide anim- -'formed*within the plugmember 9 a recess I I0 proved ignition means capable :of bringing-a"closed-by afrang'ible disc II such as cardboard large hot'flame against:the surfacexiof the pro- 0 or-"the like placed against'an'internalshoulder pellant charge in the chamber. We carry out f1 2 of the plug."The disc I! is preferably weak- ,our'finvention by the provision of acartridge containing relatively small pieces orpellets of inflammableignition material; and wemake the from "the combustion pass at highvelocity -to create the propulsive thrust. Provision is commonly madefor igniting the charge in the chamber, and thisnnay .be.,a .flamedirected against the charge.

ing grooves Ila and III). This allows the disc If-l readily toburstopen. There is placed across this recess a-suitabIe ignition wire I3 ofthe type "adapted-to become very hot when anelectric "current passesthrough it, the ends of this wire from the burningpellets or :pa-rticlesover the *beihgsoldered or weldedtc the internal surface exposedpropellant surface. The inflammable of the plug. "Thescentral=-portionof the wire is pellets within the cartridge .may be rig-mted byscosoldered-orweldedto a -terminalmember M attached to an electricalconducting stem or lead l-5 passing-from 'the terminal through aninmeans, sulating bushing IE to a recess l1 formed in an The foregoingand other features of our inouter stem 18 of the plug member 9. Therevention will be better understood from the folcessed end is filledwith a suitable ignition charge lowing detailed description taken inconjunction such as a black powder which readily ignites with theaccompanying drawings of which: when current is passed through bothhalves of Fig. 1 is a View mostly in cross section showwire 13 byconnecting an electrical voltage source ing the nozzle end of a rocketmotor with an to stem [5 and the threads of collar l8. ignitor accordingto our invention; The inner flange of plu 9 is threaded to re- Fig. 1ais a View of the frangible disc; and ceive the end of a sleeve l9 whichmay be of a Fig. 2 is a view mostly in cross section showing suitablemetal. There is snugly fitted within the the nozzle end of a rocketmotor with an ignitor sleeve a tubular cartridge 20 closed at its outercharge according to our invention adapted to fit end 2| and filled withpellets or particles 22 of into the nozzle opening. an inflammablematerial, which may for ex- Referring to Fig. 1, there is shown thenozzle ample be broken up pieces of the same sort of end of a rocket orjet motor comprising a comcomposition from which the propellant 3 ismade, bustion chamber I, ordinarily of metal, which or may be .phenylformaldehyde-perchlorate mixmay be cylindrical in shape and closed atthe tures or blasting powder in grains. The car end which is not shownin the drawing. At tridge itself is made of an-infiammable material theopen end of the cylindrical chamber there such as cellulose nitratewhich readily burns and is screwed a cap 2 which may be generallyreleases the pellets. hemispherically shaped. The chamber of the Whenthe ignitor is ignited by closing the elecmotor is filled with a solidor semisolid type of tric circuit through terminals l5 and [8, thepropellant composition 3 which may for example Nichrome wire is heated,igniting the powder in terial so that the cartridge will ,notexplodegibut willreadily burn and send a large spray of flame be a blackpowder ignited by suitable ignition {ignitor 6 is provided extendinthrough '-'ened-'-somewhat, -'as shown in Fig. la, by weakenrecess 10.The powder readily burns through the frangible disc H and ignitespellets or particles 22 in the cartridge. The cartridge material 20likewise ignites and the burning pellets are spread over the surface 4of the propellant composition thereby providing effective ignition. Theprovision of the sleeve 19 around the-cartridge serves to retain thecartridge in position so that it will not readily be blown en masse awayfrom its position at the ignitor. i= Fig. 2 shows a modification inwhich an ignitor is placed in the exhaust nozzle of the motor. Thenozzle 5 is shown in crosssection and: flares tolarger cross sectionalareas both within and with out the most constricted throat portio'r'r'25. The nozzle material may be metal such as steel, but

'4 vention we have provided an eflicient ignitor comprising a containerwhich burns as well as the ignition material, providing an effectiveamount of flame thrown over a wide area of the surface of the propellantand insuring the ignition thereof.

Weclaim:

Y 1. Anignitor comprising a metallic head having an internal recess, ametallic sleeve fitted .within the recess and protruding therefrom, a

.cylindrical cartridge fitted within the sleeve, said cartridge havingan inflammable envelope and containing inflammable particles, afrangible diapreferably there is placed a refractory element H 26 in thenozzle at the throat.

The ignitor 21 comprises a stud 28 threadedat 36 as shown and is closedat its outer end. by a=.= suitable covering such as a mesh. or gauze 31.

The conical member 34 and 36 is madeof an-inflammable substance such ascellulose acetate and the portion of it between diaphragm and the Theshape of the conical member is such that it fits within the throat ofthe nozzle; as-shown and is held in position by washer 29.- To'enableposition as shown before the cap Z is applied to the combustion chamberand then -the washer 29 is screwed onto the stud. I

In operation, the closing of the circuit wires 30 and 3| across asourceof potential'ignites the black powder which fires the inflammablepellets, throwing the flame from themagainst the 1 propellant surface 4.The conical member burns and the rest of the ignitor comprising the stud28 and washer 29 are blown out by the force of-the blast. I

' It will be recognized that according to our in- ..phragm at the end ofthe cartridge which is in- 15 serted within the sleeve and separatingthe internal portion of the cartridge from the recess, an inflammablepowder within the recess, and means for igniting the inflammable powder.

. 2.-' An i'gnitor comprising a head having an internal recess, a sleevefitted within the recess and protruding therefrom, a cylindricalcartridge fitted within the sleeve and having an end pro- I truding fromthe sleeve, said cartridge having an -inflammable envelope andcontaining inflamend 31 is filled with the inflammable pellets 0!;3

' pieces 38.

mable particles, a frangible diaphragm at the end of the cartridge whichis inserted within the sleeve and separating the cartridge from therecess, an inflammable powder within the recess,

and means for igniting the pwoder.

3. An ignitor according to claim 2 in which the sleeve is threaded intothe recess and the end of "he sleeve which is within the recess holdsthe diaphragm against a shoulder of the head.v

. FRED S. MILLER.

COLMAN ZOLA.

REFERENCES CITED I The following references are of record in the file ofthis patent:

the ignitor to be installed it may be inserted inc-3. r

I UNITED STATES PATENTS Number Name Date 7 455,278. Cunningham June 30,1891 1,791,0.49 ,White Feb. 3, 1931 1,933,694 .Allen Nov. '7, 19332,289,318. Pratt July 7, 1942 ..2 ,398,68 3. Whitworth Apr. 16, 1946FOREIGN PATENTS Number. Country Date 2,554 Great Britain July 3, 187714,000, Great Britain June 24, 1896

